Emission Factors and Constituent Characteristics of PM2.5 from Cow Dung Combustion in Qinghai-Tibet Plateau.

Cow dung is the most familiar and commonly used domestic fuel in the Qinghai-Tibet Plateau, and the atmospheric pollutants emitted due to burning cow-dung affect the atmospheric environment of the Qinghai-Tibet Plateau. In this study, in order to acquire the emission factors and constituent characteristics of PM_2.5 in association with cow-dung combastion in different seasons and at different altitudes, a series of researches were carried out in Linzhi City, Naqu City and Linzhou County of Lahsa City. By use of the dilution channel method PM_2.5 generated from buring cow-dung was collected and analyzed in terms of constituent. The results showed that in spring PM_2.5 emission factors of Linzhi, Linzhou and Naqu were (6.260±0.870) g/kg, (8.204±2.085) g/kg and (8.281 ±0.300) g/kg, respectively, and in summer, the PM_2.5 emission factors of Linzhi, Linzhou and Naqu were (6.426± 1.761) g/kg, (7.669±2.005) g/kg and (11.912± 1.741) g/kg, respectively; the relative humidity in summer was higher than that in spring, and the PM2.5 emission factors of Linzhi and Linzhou differed not very much in spring and summer, while the emission factors of Naqu in summer were slightly greater than those in spring. With the increase of altitude, atmospheric oxygen content declined, and the PM_2.5 emission factor went up. As to the PM_2.5 constituent characteristics of cow-dung combastion, the carbon content of PM_2.5 was in the range of 59.7%~77.8%, water-soluble ions 17.8%~31.4%, and metal elements 3.21%~5.09%; as to organic carbon (OC) and elementary carbon (EC), the content of OC in PM_2.5 increased with altitude, and the ratio of OC to EC ranged from 31.35 to 42.16; in regard to PO₄^3- in PM_2.5, which originated mainly from the application of phosphate fertilizer, the content of which was much higher than that of other water-soluble ions, and the proportion of PO₄^3- ranged 5.34%~10.16%. Besides, there was a significant linear correlation between the reconstructed mass and the membrane sampling mass, the correlation coefficient R² ranged 0.7238~0.961 5; and the result of reconstructed mass suggested that the PM_2.5 derived from cow-dung combustion was mainly composed of organic matter, mineral components and phosphate. [ABSTRACT FROM AUTHOR]